Conventional electronic devices are often provided with a fan for cooling electronic parts included therein. The fan mounted in electronic devices reduces heat generation of electronic parts caused by the operation of the electronic devices and ambient environments, for example. This reduction makes it possible to prevent failure of electronic devices due to heat generation and to prevent burns and other injuries caused when a user touches a high-temperature electronic device.
Recently, electronic devices having various functions are being produced, and therefore the number of electronic parts required for the electronic device is increasing. Additionally, electronic devices are being reduced in size, and therefore a resistance to an airflow generated by the fan has been increasing. As a result, the rotational speed of fans is increasing, which causes a problem of noise due to the operating sound of fans. To address this, it is preferable that, for an electronic device that needs reduction in noise, appropriate cooling design, fan selection, and control of the rotational speed of a fan, for example, be investigated at the design phase of the electronic device.
An example of a method of predicting noise caused by a fan mounted in an electronic device is a method of predicting noise on the basis of sound pressure level values at a distance of 1 meter from the front on the intake air side of the fan at rotation speeds under no load conditions and under rated load conditions that are offered by a fan manufacturer or the like. Another example of a method of predicting noise caused by a fan mounted in an electronic device is an approach of predicting on the basis of loading noise at an operating point. To predict noise of a fan mounted in an electronic device with higher accuracy, a sound pressure level value, a sound intensity value, and other characteristic values at a plurality of locations are required.
More recently, there has been a technique of predicting a pressure difference between the front and rear of a fan at the operating point by means of thermal analysis so as to predict the loading noise and the amount of air flow at the operating point from the loading noise, the PQ characteristic, and the like of the fan. The term “loading noise” refers to the level of sound under conditions where loads are applied to the airflow passage of a fan.
Japanese Unexamined Patent Application Publication No. 2001-108642 is an example of related art.